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Topic: Chris's Marion 91 Steam Shovel (Read 249958 times)

Next stage on the dipper boom was to bolt on the holders for the top braces (had not put on the newer smaller nuts when this pic was taken).Then milled down some bar stock to size for the angle braces, left long, and heat-bent them to shape. They were held in the vise at the opposite end from the bend, heated red with a torch, and bent over with some pliers. Took a couple of heats to get the bend due to the thickness of the bars and how fast they cooled. With some minor tweaks, got them to be straight into the brackets at the bucket end, and parallel to the boom at the other.Then drilled the bucket end for the cross pin and filed the end round. With the bucket set to the proper angle to the boom with a protractor (the bucket is not at 90 degrees, it is tipped forward several degrees to give it better bite into the ground), the other end was marked at the bracket on the boom, and drilled there. With the one side pinned in place, the other side was marked and drilled to match - this is one of those times where marking from the actual parts beats marking from the distance on the plance, with this many parts in between the tolerances can build up too fast (at least for me).As you can see, I've stripped the original paint off the bucket shell - it was not holding up that well to handling, so it will get repainted along with the boom with the new bake-on enamel that I tested on the bottom door, which is holding up great so far.Here it all is with the bucket pinned in place, door is still off till after painting.Next up is to make the plugs at the back end of the booms, which slip into the ends of the steel wrapper and against the inner wood core. The back of the plugs are a half-round shape, so am setting up the rotary table again for that.After that, need to make the lever that the door chain attaches to - that bolts on to the bottom fitting near the bucket, and then I can start on the gear rack.One item that arrived this week was a print copy of the 1902 Marion steam shovel catalog that I obtained. One tidbit of information in there (among many, they brag about all the design features the way new car brochures do today), was a discussion of why they used the wood cores in the booms. I had seen references before that it helped prevent fracturing the steel, which could happen with an all-steel boom, but in this writeup they also mention that with an all steel boom there was a tendancy for the boom to take a permanent twist if it was flexed to one side, like if it hit a boulder on one side of the bucket during a scoop. With the wood core, they say it resists the twisting better, and rebounds back to shape better than the all steel version, though they say that they would supply an all-steel boom if requested by the buyer. Lots of interesting stuff in those catalogs. They usually have a bunch of photos of shovels in action at customer sites - I've noticed that almost every customer added their own custom features, like permenant enclosures for the coal deck, walkways down the sides (there is very little room to walk past the engines inside), one even had a wood tower on top with a big light, presumably for working at night.

In looking at the bucket photos and in person, it seemed chunky, so I checked the photos of the real one and I realized I missed something on the yoke that spans the bucket - the thickness (front to back) at the bottom is correct, but I forgot to include the taper that it has, at the top where the pulley attaches it should be thinner. So, before painting I need to take the yoke off and do a little milling on it.

" With the wood core, they say it resists the twisting better, and rebounds back to shape better than the all steel version"

Interesting reporting from the manufacturer Chris......do they talk about a particular wood specie?..[we have soft woods to iron bark which range dramatically in density and mechanical properties]

We see you have a bolted [one piece] Oak block of wood at the bucket end within the dipper boom boxed structure, will you be replacing this with longitudinal laminated sections which would be as per actual build?...or would a one piece section of wood have been used?

This also brings the direction of the growth lines within the timber to best resist the rotational twisting moment imposed on the box section of the dipper boom

" With the wood core, they say it resists the twisting better, and rebounds back to shape better than the all steel version"

Interesting reporting from the manufacturer Chris......do they talk about a particular wood specie?..[we have soft woods to iron bark which range dramatically in density and mechanical properties]

We see you have a bolted [one piece] Oak block of wood at the bucket end within the dipper boom boxed structure, will you be replacing this with longitudinal laminated sections which would be as per actual build?...or would a one piece section of wood have been used?

This also brings the direction of the growth lines within the timber to best resist the rotational twisting moment imposed on the box section of the dipper boom

Derek

Hi Derek,

They say they use white oak for all the wood parts. They used single blocks, not laminations, for the blocks. The main boom is constructed the same way as the dipper, just larger. On the smallest machines, the booms were wood only in some cases, where medium and large ones all had the wrapped wood. On the shovel here, the center spacer block at the base of the main boom has a lot of rot on the top surface, but its still a massive block. The center blocks appear to be solid chunks, this predates glue lam beams. Hard to say which way they oriented the grain inside the booms, if anything specific, since it is wrapped, and I'd get in a lot of trouble if I took it apart!!

Will you please slow down? I, for one, cannot keep up.Go make some cookies. Do some carving. Swim with your subs. Provide some quality play time with your elves.

Try to reach my level of progress.

Reminds me of the old joke, I'll type slow since I know you don't read fast!

And this IS slow progress! I also spend a lot of time on two archery leagues, pistol league, two rifle leagues, am building the turtle sub, watching TV, taking care of my mom, eating cookies, researching Marion shovels, napping, reading, carving, running subs, ... Not my fault that you are still in that silly universe with only 24 hours in a day! Retire already!!

They say they use white oak for all the wood parts. They used single blocks, not laminations, for the blocks. The main boom is constructed the same way as the dipper, just larger. On the smallest machines, the booms were wood only in some cases, where medium and large ones all had the wrapped wood. On the shovel here, the center spacer block at the base of the main boom has a lot of rot on the top surface, but its still a massive block. The center blocks appear to be solid chunks, this predates glue lam beams. Hard to say which way they oriented the grain inside the booms, if anything specific, since it is wrapped, and I'd get in a lot of trouble if I took it apart!!

I can see the logic in using the timber core for its resilience, and anyone who has come across old oak beams will know how tough it is. I guess they would have used straight-grained, well-seasoned wood to avoid any tendency for warping or twisting as it aged. There would seem to be ideal conditions for moisture to be trapped within the booms, resulting in corrosion of the metal in such close contact. But it obviously couldn't have been a major problem if they used it routinely - maybe there would not be enough oxygen in there for serious rusting to occur

Like everybody here I am still following along with a mixture of envy, respect and wonder